Enhanced Dedicated Channel (E-DCH—also known as High-Speed Uplink Packet Access—HSUPA) is a transport uplink channel used in the UMTS technology to improve capacity and data throughput and reduce the delays in dedicated channels in the uplink (UL). The maximum theoretical uplink (UL) data rate that can be achieved using HSUPA is 5.7 Mbps through the use of Quadrature Phase Shift Keying (QPSK) modulation and a 2 ms TTI (Transmission Time Interval) in a unique cell of the Universal Mobile Telecommunications System (UMTS).
In 3GPP Release 7, the use of 16QAM (Quadrature amplitude modulation) on the E-DCH was introduced, enabling the possibility of doubling the peak rate. And finally, in 3GPP Release 9, the possibility of transmitting on more than one UTRA channel/cell simultaneously was introduced. This enables the possibility of transmitting in two carriers/cells at the same time, so in case of no limit in the User Equipment (UE) power and sufficient data to use up both of the cell resources in the two carriers, the data rate may be doubled in a specific place. This is known as dual cell mode for HSUPA.
Switching from single cell to dual cell mode entails higher power consumption for the UEs due to the higher control plane overhead and also higher user plane throughput. Furthermore, switching from single cell to dual cell mode could sometimes lead to cell overload if not managed properly; in many cases the data rate needed for the UL could be borne by a single cell not requiring any switching to dual cell mode of operation on UL.
The problem is to know when it is more efficient to move to dual cell transmission from single cell transmission, and vice versa and exisiting solutions are static, not dynamic depending on the connections and radio conditions